U.S. Pat. No. 3,600,204 teaches a lower thermal expansion ceramic material for heat regenerator applications, namely, a lithium aluminosilicate (LAS) glass powder which is cerammed to low expansion beta-spodumene phase assemblage upon firing. The process of melting the batches to form LAS glass powders is a very expensive route to producing ceramic honeycombs due to the costs associated with the high temperature melting and powdering of glass into appropriate particle sizes. In addition, the extrusion of such glass powders is difficult, requiring large amounts of binders and plasticizers. There are difficulties in controlling the uniform crystallization process.
U.S. Pat. No. 5,403,787 relates to utilizing a mixture of glass and mineral batches for extruding and firing to produce low expansion LAS ceramic honeycombs. However, the contemplated extrusion batches still contain major portions of LAS glass powders and only 2-30% by weight of aluminosilicate clays.
It would be desirable and an advancement in the art to have a method of producing beta-spodumene bodies having the low expansion and high strength derived from primarily mineral batches with some low temperature melting glass, without incurring high costs especially those attributed to the glass constituent.
The present invention provides such a method by a material formulation, shaping, and reactive ceramming of primarily mineral batches with a minor amount of selected glass.